1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition suitable for microprocessing using various types of radiation such as deep ultraviolet radiation, electron beams, and X-rays.
2. Description of Background Art
A recent strong demand for high density and highly integrated LSIs (large-scale integrated circuits) radically accelerates miniaturization of wiring patterns.
Using short wave rays in a lithographic process is one method for miniaturizing wiring patterns. In recent years, deep ultraviolet rays typified by a KrF excimer laser (wavelength: 248 nm) or an ArF excimer laser (wavelength: 193 nm), electron beams, X rays, and the like are being used in place of ultraviolet rays such as g-line (wavelength: 436 nm) and i-line (wavelength: 365 nm).
Novolac resins, poly(vinylphenol), and the like have been used as resin components for conventional resist compositions. However, since these resins exhibit strong absorbance at a wavelength of 193 nm due to inclusion of aromatic rings in the structure, a lithographic process by an ArF excimer laser using these resins cannot provide high accuracy corresponding to high photosensitivity, high resolution, and a high aspect ratio.
Therefore, a resin for use in a resist, transparent to a wavelength of 193 nm or less and exhibiting dry etching resistance equivalent to or more excellent than aromatic rings, has been desired. A siloxane polymer is one such resin. R. R. Kunz et al. of the MIT have reported their research results showing excellent transparency of a polysiloxane wat a wavelength of 193 nm or less, particularly at 157 nm, commenting on superiority of this polymer as a resist material in a lithographic process using radiation at a wavelength of 193 nm or less (J. Photopolym. Sci. Technol., Vol. 12, No. 4, 1999). Moreover, polysiloxanes are known to exhibit excellent dry etching resistance. In particular, a resist containing polyorganosilsesquioxane having a ladder structure is known to possess high plasma resistance.
Several resist materials using a siloxane polymer have also been reported. For example, Japanese Patent Application Laid-open No. 323611/1993 discloses a radiation-sensitive resin composition comprising a polysiloxane having an acid-dissociable group such as a carboxylic acid ester group, phenol ether group, etc., on the side chain, bonded to a silicon atom via one or more carbon atoms. Japanese Patent Application Laid-open No. 160623/1996 discloses a positive tone resist using a polymer in which the carboxyl group of poly(2-carboxyethylsiloxane) is protected with an acid-dissociable group such as a t-butyl group. Japanese Patent Application Laid-open No. 60733/1999 discloses a resist resin composition in which a polyorganosilsesquioxane having an acid-decomposable ester group is used.
However, conventional resist materials using a siloxane polymer have not been satisfactory, particularly in the resolution performance.
An object of the present invention relates to a radiation-sensitive resin composition comprising an acid-dissociable group-containing polysiloxane as a resin component and suitable for use particularly as a chemically-amplified resist with excellent resolution.